The purpose of this study is to evaluate regional V/Q mismatch at rest and during exercise. Our study utilized ^<99m>Tc-macroaggregate albumin to determine distribution of pulmonary blood flow. We used ^<81m> Kr gas to determine resting and exercise ventilation. In 40 cases of various lung deseases ventilation and perfusion images were obtained by simultaneous acquisition from both anterior and posterior surface of patients. With data processing computer GMS-550U distribution of V/Q at each of 128X128 matrix was calculated. Histogram of frequency of V/Q distribution was examined with reference to blood gas analysis and general lung function test. In 15 patients of various lung deseases histogram of frequency of V/Q distribution of SPECT was compared with that of superimposed image from the simultaneous anterior and posterio_2 data acquisition. Correlation between the proportion of V/Q mismatch and A-aDO_2 was examined. V/Q mismatch was made to be within V/Q <0.67 and/or >1.50 in V/Q hi
… Morestogram. Percentage of V/Q mismatch counts to total counts in histogram was calculated. THere were coefficients of correlation of 0.684(p <0.05) in a terior images, 0.654(p <0.05) in posterior images and 0.696(p <0.05) in superimposed images between percentage of V/Q mismatch in the histogram and A-aDO_2.The superimposed images showed the highest corelation. No orrelation between general lung function data and A-aDO_2 was observed.There exisisted significant corelation(r=0.888, p <0.001) between the percentage of V/Q mismatch calculated from SPECT.Dual planner acqusition method relative to the SPECT is useful in showing simple method and shortening of examination time.The effects of exercise on V/Q distribution in 5 normal sunjects, 13 patients of pulmonary tuberculosis and a patient of COPD were studied. V/Q mismatch in COPD was much more influenced by exercise than in healthy subjects and patients of pulmonary tuberculosis.For ventilation study intrapulmonary distribution of _<99m> T c-tchnegas was similar to that of _<81m> K r gas, although there existed mild gravitational effect. Less